"My mother is sitting on the chair."
Translation:मेरी माँ कुर्सी पर बैठी हैं ।
See the little hook at the top-right of कुर्सी? That's what gives the "r" sound. It's called रेफ (reph). र (ra) is the only letter to have a special, diacritic-like form when it occurs as the first component of a consonant cluster. It's written on the top of the letter before which it is pronounced. Here are a few examples.
तर्क (tark) - argument
अर्थ (arth) - meaning
स्पर्धा (spardhaa) - competition
गर्मी (garmi) - heat, summer
ऊर्जा (oorjaa) - energy